A Highly Accurate Solenoid Valve Driver Using Midpoint Current Sensing Method for Automotive Applications

In this paper, we propose a highly accurate low-side solenoid valve driver with a current sense-and-mirror circuit for electric brake booster systems in automotive applications. The proposed low-side solenoid valve driver employs a midpoint current sensing method, which senses the solenoid coil currents at the moment when it is turned on and off, and averages the sensed currents, thus achieving a highly accurate current. In addition, it integrates only a low-side power MOS transistor into the chip, thus reducing the power dissipation. The proposed low-side solenoid valve driver was fabricated using a 0.11 mu m Bipolar-CMOS-DMOS (BCDMOS) process. The measurement results show that the current accuracy of the proposed low-side solenoid valve driver was improved by up to 8% compared with that of the conventional Ton/2 current sensing method. In addition, the power dissipation of the proposed solenoid valve driver was reduced to 44% less than that of the conventional high- and low-side solenoid valve driver. Therefore, the proposed solenoid valve driver is suitable for electric brake booster systems requiring highly accurate current and low power dissipation.